Input: ab8500-ponkey - switch to using managed resources

Let's switch the driver to use managed resources, this will simplify
error handling and driver unbinding logic.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>